1results about How to "Short filter time" patented technology

This invention discloses a method for removing impurities from ferrous sulfate, a byproduct of titanium dioxide production, comprising the following steps: 1) taking ferrous sulfate and preparing a saturated solution; 2) adding dilute phosphoric acid, stirring thoroughly, and filtering to remove insoluble matter; 3) adding an appropriate amount of ammonia to the obtained solution, filtering, and evaporating the filtrate; 4) slowly stirring and cooling the remaining solution until the solution temperature drops to 10°C, centrifuging to obtain primary crystals and primary crystallization mother liquor; 5) dissolving the obtained primary crystals again and preparing a saturated solution, repeating steps 3) and 4) to obtain secondary crystals and secondary crystallization mother liquor; 6) dissolving the secondary crystals to prepare a ferrous sulfate solution, which can be directly used for the preparation of battery-grade iron phosphate. This method uses phosphoric acid, ammoniation, and recrystallization to remove impurities from ferrous sulfate through multiple processes. After impurity removal, the heptahydrate ferrous sulfate solid has high purity and low metal impurity content, and can be directly used for the synthesis of battery-grade iron phosphate after dissolution.